Container for radioactive materials having a heat releasable outer panel wall

ABSTRACT

A container for radioactive materials comprising a chamber provided with a wall carrying outwardly projecting cooling elements such as fins. A casing is provided around the wall and means are provided for passing cooling fluid through the space between the wall and casing, which space contains the cooling elements. Preferably the casing comprises a plurality of panels secured to the wall but adapted to eject away from the container should the cooling air flow means fail. A preferred securing/ejection means comprises studs which melt on failure of the airflow means and springs ejecting the panels.

United Stati Bochard 1 Jan. 16 1973 I CONTAINER FOR RADIOACTIVE MATERIALS HAVING A HEAT Primary Examiner-Archie R. Borchelt RELEASABLE OUTER PANEL WALL Almmey-Alexander & Dowel] [75] Inventor: Camille Bochard, Lyon, France I 57] ABSTRACT Assignee: Robatel Rhone A container for radioactive materials comprising a V nw chamber provided with a wall carrying outwardly pro- 2 9 19 1 jecting cooling elements such as fins. A casin is pro- [22] iled g vided around the wall and means are provided for [21] Appl- 113,940 passing cooling fluid through the space between the wall and casing, which space contains the cooling ele- "250/108 ments. Preferably the casing comprises a plurality of panels Secured to the wall but adapted to eject y [58] Field of Search ..250/108 R, 108 WS from the Container should the Cooling air flow means fail. A preferred securing/ejection means comprises [56] References cued studs which melt on failure of the airflow means and UNITED STATES PATENTS Springs j t the panels 3,] 1 1,5 86 l1/l963 Rogers ..250/l08 R 4 Claims, 5 Drawing Figures 3,39 l .280 7/1968 Bonilla et al ESQ/I08 R CONTAINER FOR RADIOACTIVE MATERIALS HAVING A HEAT RELEASABLE OUTER PANEL WALL This invention relates to containers for radioactive materials.

In order to improve dissipation of the heat evolved by a radioactive material stored in a container the outer wall of the container is generally provided with cooling pins or fins which increase the surface area of the wall and, hence, the rate of loss of heat to the ambient air. However, this does not always improve the heat dissipation enough and increasing the number of cooling pins or fins simply results in a reduction of the free space between these elements for the passage of the air and does not improve the heat loss beyond a certain maximum. Under these conditions, when the material is likely to evolve an appreciable amount of heat, it is necessary in practice to use a container of a larger size and greater weight than would otherwise berequired for the volume of the material to be transported.

We have now devised a container from which heat can be dissipated more quickly than from the containers described above.

According to the invention, there is provided a container for radioactive materials which comprises an inner wall comprising a radioactive shielding material, the wall being provided on its outer surface with a plurality of cooling projections, and an outer wall spaced from the said outer surface of the inner wall and forming therewith a jacket through which coolant fluid can be passed.

Preferably, the casing is demountable.

A suitable coolant fluid is air and in one embodiment of the invention, the jacket is operatively connected with a fan which either blows or sucks air through the jacket.

Preferably, the outer wall is formed of two or more releasable panel members and, preferably, at least some of the panel members are secured to the said inner wall by jointing members which are arranged to release the panels when the temperature of the members reaches a predetermined level.

In order that the invention may be better understood, a preferred embodiment will now be described, by way of illustration only, with reference to the accompanying drawings in which:

FIG. I is an elevation and partial vertical section of a container according to the invention;

FIG. 2 is a cross-section on the line Il-Il of FIG. 1;

FIG. 3 is a perspective view of one of the panels forming the casing of the container shown in FIGS. 1 and 2;

FIG. 4 is a cross-section to an enlarged scale showing the fixing of one of these panels to the chamber wall of the container; and

FIG. 5 is a diagrammatic section showing the connecting elements illustrated in FIG. 4 at the moment of the ejection of the panels.

With reference to FIGS. I and 2, the container comprises, as is conventional, an outer metal wall I of circular section, inside which is fixed a screen or shielding 2 formed by a mass of lead. The central part of this screen 2 encloses a jacket 3 to accommodate the rod or other radioactive component to be transported. The container assembly rests on a base 4 while its other end or fan indicated at 8. In the embodiment illustrated, the

casing consists of eight panels 9 which are identical to one another. As illustrated in FIG. 3, each of these panels (which are preferably made from plastic laminate or thin sheet-metal) has a curved profile extending over a arc of a circle, the longitudinal edges and one of the transverse edges being provided with a rim 9a, 9b respectively directed outwardly. The panels 9 are also associated (as is generally preferred) with a band or hoop 10 on the outside, of a radius slightly greater than that of the panels and suitably connected to the conduits 7. This band or hoop is formed from two U-section members, the U being open towards the interior, each of the two members extending over a substantially arc of a circle and being connected together in sealing-tight relationship at their facing ends. The band or hoop 10, disposed in the central part of the container, is fixed to the wall I by any suitable means, e.g. screwthreaded studs (not shown) which are connected to the wall l and extend through the center web of the U-sections to receive clamping nuts.

As is generally preferred, each panel 9 is connected to the outer wall l by means of a radial chimney 11 (FIGS. 4 and 5) which is appropriately welded to the wall between the cooling pins 6. The outer enlarged end Illa of this chimney bears a number (in this case four) of screwthreaded studs 12 which are introduced through apertures formed in the edge of a closure cap 13 provided with a gasket 13a; the studs 12 receive nuts 14 adapted to hold the cap 13 and they extend through perforations 9c in each panel 9 and their projecting end is provided with a nut, e.g. IS. The studs 12 are made from a material having a low melting point (for example a metal alloy or a plastic) so as to melt in the event of the temperature rising above a certain value, with the result that the panels 9 are then released. A spring 16 compressed between the wall I and the cap 13 is disposed inside the chimney I I.

The transverse rim 9b of each panel 9 is applied laterally against the band or hoop 10 while the longitudinal rims 9a are fitted against one another in substantially sealing-tight relationship as shown in FIG. 2. The conduits 7 lead to the interior of the band or hoop 10 so that the air delivered by the blower 8 is distributed evenly in the annular space between the wall 1 and the inner surface of the panels 9 forming the cooling cas ing, the air finally escaping at the base 4 and lid 5 of the container. The pins 6 are thus subjected to a continuous stream of cooling air.

In the event of, or following any damage or accident such as would happen if the blower 8 stops or the conduits 7 become torn away or clogged, the stoppage of the cooling air stream would cause the temperature in the space between wall I and panels 9 to rise and result in melting of the fixing studs 12 (FIG. 5). The springs 16 would then eject the caps 13 and the panels 9, container cooling then being carried out by natural convection of the ambient air over the pins 6. The pins 6 should, of course, be designed so that in such a case the heat dissipation is sufficient for the temperature inside the container to be less than the melting temperature of the lead screen or shielding 3.

The container according to the invention has the advantage that it can be used for the transportation and/or containment of radioactive materials evolving a considerable amount of heat, without the temperature exceeding an acceptable limit and without it being necessary for the size and weight of the container to be excessive. The time required for thermal equilibrium to be established after loading is also greatly reduced while unloading of the container in the swimming pool can be carried out immediately after reception, the container being at a sufficiently low temperature to be immersed without prior cooling. This gives an appreciable saving of time in loading and unloading operations.

The invention can be applied to containers having any conventional section and to those in which the cooling means consist of fins. Depending upon the container profile, one or more distribution bands or hoops 10 will be provided and be disposed in the central part or near the ends of the wall 1; in some cases, each band or hoop may consist of a rectangular or square section member, that wall which faces the interior of the container being formed with apertures for the admission of air the convection casing formed by the panels 9.

lclaim:

1. A container for radioactive materials which comprises an inner wall comprising a radioactive shielding 5 jacket surrounding said inner wall, the outer surface having at least one fluid inlet port therein and at least one fluid exit port therein; said outer wall being formed of at least two releasable panel members; and jointing members securing at least some of the said panel members to the said inner wall, said jointing members being arranged to release the panels when the temperature of the said members exceeds a predetermined level.

2. A container according to claim 1, said jointing members comprising a material which melts at a predetermined level to cause the panels to be released,

and wherein spring means are provided in said jacket to eject the released panels from the outer wall.

3. A container for radioactive material which comprises a chamber for containing radioactive material, said chamber having side wall means comprising lead shielding material, said side wall means having an outer surface, the outer surface having thereon a plurality of cooling projections, said container also comprising demountable casing means spaced from and surrounding the outer surface of the said side wall means and forming therewith a cooling fluid chamber, the said casing including port means for allowing cooling fluid to enter and to leave said ,fluid chamber; said casing means comprising a plurality of panel members, and low melting material members securing said panel members in fixed relation to said side wall means.

4. A container according to claim 3 wherein spring means are provided under compression to urge said panel members away from said side wall means. 

1. A container for radioactive materials which comprises an inner wall comprising a radioactive shielding material having an outer and an inner surface, the said outer surface having a plurality of cooling projections thereon, and an outer wall spaced from the said outer surface of the said inner wall and defining therewith a jacket surrounding said inner wall, the outer surface having at least one fluid inlet port therein and at least one fluid exit port therein; said outer wall being formed of at least two releasable panel members; and jointing members securing at least some of the said panel members to the said inner wall, said jointing members being arranged to release the panels when the temperature of the said members exceeds a predetermined level.
 2. A container according to claim 1, said jointing members comprising a material which melts at a predetermined level to cause the panels to be released, and wherein spring means are provided in said jacket to eject the released panels from the outer wall.
 3. A container for radioactive material which comprises a chamber for containing radioactive material, said chamber having side wall means comprising lead shielding material, said side wall means having an outer surface, the outer surface having thereon a plurality of cooling projections, said container also comprising demountable casing means spaced from and surrounding the outer surface of the said side wall means and forming therewith a cooling fluid chamber, the said casing including port means for allowing cooling fluid to enter and to leave said fluid chamber; said casing means comprising a plurality of panel members, and low melting material members securing said panel members in fixed relation to said side wall means.
 4. A container according to claim 3 wherein spring means are provided under compression to urge said panel members away from said side wall means. 